Photosensitive material

ABSTRACT

A photosensitive layer capable of producing a physically developed contrast containing a significantly decreased number of pinholes in which a non-conducting support is provided with a photosensitive diazosulfonate, mercurous ion and/or silver ions and a saccharade having an aldehyde group.

United States Patent 1191 11] 3,802,886 Spiertz et al. 1 Apr. 9, 1974 [51 PHOTOSENSITIVE MATERIAL 2,735,773 2/1956 Dippel et al. .[96/48 PD2.838398 6/l958 Di el et l. 96/49 [75] Invent: Ellsabe f 5PM"; Leende3,086,833 4/1963 $622k 8/79 Klaas Bellmga Y Beek both of 3,159,48712/1964 Kreiger et a]. 96/75 Emmasmg Emdh n, 3,390,998 7/1968 0:16 96/48PD Netherlands 3,409,438 11/1968 Lokker 96/49 3,464, 2 9 9 H l [73]Assigneel Philips Cmlmafio"! New 3.50624; 4x95 32m York, 3,615,56010/1971 Jonker et al 96/75 [21] PP N95 234,408 Kosar, J.,Light-Sensitive Systems," Wiley 8: Sons,

Related U.S. Application Data 1965, PP- 255, 292, 294 and [63]Continuation of Ser. No. 865,958, Oct. 13, 1969,

abandoned. Primary ExaminerCharles L. Bowers, Jr.

Attorney, Agent, or Firm-Norman N. Spain; Frank R. [30] ForeignApplication Priority Data Trifari Oct. 26, 1968 Netherlands 6814762 I[57] ABSTRACT [52] U.S. Cl. 96/75, 96/36.2, 96/48 PD, 96/49 96/86 R96/87 R, 96/91 R A photosensltlve layer capable of producmg a physi- 511m. (:1 G036 1/56, G036: 1/76 Cally developed Contrast Containing aSignificantly [58] Field Of Search 96/48 PD, 49, 75, 91 R creased numberpinholes in which a conducting support is provided with a photosensitive[56] References Cited diazosulfonate, mercurous ion and/or silver ionsand 21 UNITED STATES PATENTS saccharade having an aldehyde group.2,657,137 10/1953 Kessels 96/91 R 5 Claims, N0 Drawings PHOTOSENSITIVEMATERIAL This is a continuation, division, of application Ser. No.865,958, filed Oct. 13, 1969 now abandoned.

The invention relates to photosensitive material comprising an at leastsuperficially electrically nonconducting support in which or on whichthe actual photosensitive layer comprising a stable aromaticdiazosulphonate is provided.

Known materials comprises as a photosensitive substance, an aromaticdiazo compound, for example, a diazo thioether or a diazosulphonate or adiazocyanide. The action of these diazo compounds, when being used inphotographic material, is based on the recognition that they yield anunstable intermediate product upon exposure, which can at leastpartially dissociate into diazonium ions and anions, in theabovementioned case alkyl thiolate, sulphite and cyanide, respectively.When an exposed layer comprising such a diazo compound is contacted withan aqueous solution containing mercurous ions and preferably also silverions, a latent image is formed which consists of physically developablemercury or amalgam nuclei, because the said unstable intermediateproducts and/ or the anions produced during dissociation are capable ofwithdrawing mercuric ions from the equilibrium:

which exists in a satisfactorily prepared solution of a mercurous salt.In an embodiment of the diazosulphonate material (Netherlands Pat.application 6.606,656) the mercurous salt and the silver salt arealready present in the photosensitive layer, so that the said nucleationis directly set in during exposure in a layer which is not completelydry. The metal nuclei images formed are intensified by physicaldevelopment to photographic metal images of the required blackening.

A diazosulphonate layer preferably comprises also a so-calledanti-regression agent, which is a compound which, prior to thenucleation reaction having taken place, prevents the diazo compound frombeing reformed from its light reaction product by binding either thediazonium ion or the sulphite ion or both ions in such a manner that thesulphite ion retains the possibility to react with mercurous ions in thepresence of moisture while forming mercury nuclei these antiregressionagents are described and a large number of them are listed in BritishPat. 748,172, published Apr. 18, 1956.

The photosensitive layer may be obtained, for example, by saponificationof a surface layer of a foil consisting of a cellulose ester, or byanodic oxidation of an aluminium foil succeeded by impregnation of thehydrophilic layer obtained with a solution comprising the photosensitivesubstance and possibly the auxiliary substances. It may alternativelycomprise a larger or smaller part of a hydrophilic support, such aspaper or cellophane. The material may furthermore consist of a supportof dimensionally stable material which cannot be impregnated with water,and which is provided with a hydrophilic photosensitized layer.

It has been found that inhomogeneities in the photosensitive layer giverise to the formation of small holes of microscopic dimensions. Suchinhomogeneities may occur, for example, when the diazo compounds are nothomogeneously distributed in the layer. Much more important was thephenomenon that also the light reaction product may cause depositformation in'the layer which in some known modifications is stilladvanced by the presence of metal ions which with the anions producedduring exposure yield sparingly soluble salts. Such inhomogeneities inthe layer are insufficiently reactive at the nucleation reaction andprobably cause the occurrence of small holes of microscopic dimensionsin the developed image. The number of these holes was unfortunatelyfound to be greatest in those photosensitive materials which due totheir high resolving power might eminently be suitable for themanufacture of photomasks for integrated circuits. For such uses,however, the occurrence of large numbers of holes is unacceptablebecause these are transferred onto the used photosensitive etchingresists and would therefore lead to a high percentage of rejects duringmanufacture. It is true that the number of holes can be reducedconsiderably by careful choice of the support material, because it hasbeen found that plasticizers or impurities present in some foils orcertain chemically active groups in the macromolecular base indirectlyor directly cause holes. A further improvement may be obtained byworking as carefully as possible and with the exclusion of dust duringthe manufacture of the foils. All these steps combined cannot, however,decrease the level of the number of holes per sq.cm any further than toseveral thousand, counted microscopically at an enlargement of 60 timesin areas of blackening D 3.5. This is, however, still unacceptable forthe above-mentioned uses.

The material according to the invention provides a developed imagewhich, in areas of blackening D 3.5'

important for practice, has a number of holes per sq.cm asmicroscopically observed at an enlargement of 60 times which as a ruleis considerably smaller than 1,000. It is characterized in that inaddition to an aromatic diazosulphonate, an antiregression agent, andpossibly buffers and/or mercurous ions and silver ions, thephotosensitive layer comprises a saccharide having an aldehyde function.

Such a saccharide, which is preferred on account of its greatestactivity, is maltose, since it gives a number of holes of far less than1,000. In the embodiment in which mercurous and silver ions are presentin the layer, maltose is preferably used in a molecular concentrationwhich is at most one-fourth of that of diazosulphonate. Lactose,glucose, galactose and starch are also suitable, but they have a smalleractivity than maltose. The presence of an aldehyde function in themolecule has been found to be essential: hence, saccharose does not showany effect at all.

According to a further elaboration of the invention it was found than anadditional reduction of the number of holes is obtained when thesolution by which the layer is photosensitized also comprises anon-ionic wetting agent in a concentration of at least 0.1 percent byweight.

The added saccharides and wetting agents probably enhance thedistribution of the light reaction product in the layer so that the riskof the occurrence of concentration gradients and hence the possibilityof deposit formation is reduced. There is evidence that the saccharideshaving an aldehyde function slightly bind the sulphite, although this isdenied in literature (A.F. Holleman Leerboek der Organische Chemie 1960,pages 368 and 401 etc.). Maltose also shows the effect of slightlyincreasing the sensitivity.

sulphonic acid, 0.1 mol cadmium lactate, 0,1 mol calcium lactate, and0,] mol lactic acid;

al. the same components as solution a 0.2 mol glucose;

a2. the same components as solution a 0.2 mol maltose;

b. the same components as solution a 0.1 percent of Lissapol N (i.e. anon-ionic surface-active substance comprising a condensation product ofalkyl phenols and ethylene oxide);

bl. the same components as solution b 0.2 mol maltose.

After removing the adhering liquid by wiping it off between two rubberstrips, the strips were dried in a hot stream of air, and subsequentlystored for approximately 12 hours in a space through which air of 50percent relative humidity flows. After exposure of the strips with theaid of a sensitometer, a nuclei image was introduced by treatment for 4seconds in a bath containing per litre of water 0.005 mol mercurousnitrate and 0.0066 mol silver nitrate, and 0.1 percent of Lissapol N.Subsequently the strips were rinsed for a short time in deionized waterand developed for 4minutes in a physical developer containing per litreof water: 0.05 mol. ferrous ammonium sulphate, 0.01 mol ferric nitrate,0.1 mol citric acid, 0.2 g of Armac 12D, (i.e., a cationicsurface-active substance which consists for approximately 90 percent ofdodecylamine acetate, for 9 percent of tetradecylamine acetate andfurthermore of higher alkylamine acetates) and 0.2 g of Lissapol N.

After rinsing in deionized water and drying, the sensitometer stripswere measured with the aid of the sensitometer. In the area of densityfor visible light of D 3.5 the number of holes was counted at anenlargement of 60 times. The numbers found were multiplied by a constantfactor in order to obtain numbers per sq.cm. The results were, forstrips photosensitized with:

solution a 2,600 per sq.cm: log E 5,34

solution al 1,450 per sq.cm: log E 4,73

solution a2 550 per sq.cm: log E 4.72

solution b 1,500 per sq.cm: log E 5.10

solution bl 550 per sq.cm: log E 4.67

The exposure energies E are expressed in ergs/sq.cm.

2. Strips of saponified carrier material of Example 1 werephotosensitized with solutions containing per litre of water:

a. 0.2 mol cadmium salt of 4-methoxybenzene diazosulphonic acid, 0.005mol mercurous nitrate, 0.01 mol silver nitrate, 0.02 mol cadmium lactateand 0.1 percent of Lissapol N;

al. the same components as a 0.2 mol glucose;

a2. the same components as a 0.01 mol maltose.

After sensitometric exposure, a nuclei image was introduced by treatmentfor 4 seconds in a bath containing per litre of water 0.005 molmercurous nitrate, 0.0025 mol silver nitrate, and 0.1 percent ofLissapol N. Subsequently the strips were rinsed for 4 seconds indeionized water and developed as described under I. The results were,for strips photosensitized with:

Solution a: 2,500 per sq.cm log E 4.90

Solution al: 1,900 per sq.cm log E 4.97

Solution a2: 750 per sq.cm log E 4.68.

What is claimed is:

l. A photosensitive material suitable for physical developmentcomprising a support having a surface which is" essentially electricallynon-conductive, the surface having a photosensitive layer which containsa stable aromatic diazo-N-sulfonate, at least one saccharide containingan aldehyde moiety selected from the group consisting of maltose,lactose, glucose, galactose and starch and an antiregression agent forthe diazosulfonate.

2. The photosensitive material of claim 1 wherein in addition silver andmercurous salts are present in the photosensitive layer.

3. The photosensitive material of claim 1 wherein the saccharide ispresent in a molecular concentration that is not greater than one-fourthof that of the diaaosulfonate.

4. The photosensitive material of claim 3 wherein the saccharide ismaltose.

5. The photosensitive material of claim 4 wherein a nonionic wettingagent is present in the photosensitive layer.

NO 3502,2386 1 Dated pril -..-.L a I "in the Title page:

{30] 0ct.26,l 968 should be C'L y Elgfid and sealed this Nth-day ofSeptember 1974.

testing Office r 2-2 30! M; GIBSON, JR. I C. MARSHALL D ANN Commissionerof Patents

2. The photosensitive material of claim 1 wherein in addition silver andmercurous salts are present in the photosensitive layer.
 3. Thephotosensitive material of claim 1 wherein the saccharide is present ina molecular concentration that is not greater than one-fourth of that ofthe diazosulfonate.
 4. The photosensitive material of claim 3 whereinthe saccharide is maltose.
 5. The photosensitive material of claim 4wherein a nonionic wetting agent is present in the photosensitive layer.